Plans to slash barristers’ fees will cause “irreparable harm” to the legal system because lawyers will simply leave and “find something else to do”, senior QCs have warned.

In a letter to The Telegraph, six leading silks claimed average legal aid fees in criminal cases of £35 to £40 per hour are “significantly lower than most teachers and doctors”.

They accused Chris Grayling, the Justice Secretary, of “relying on public misconceptions” about barristers’ pay in order to introduce significant cuts to fees in state-funded cases.

The letter, signed by the leaders of the Bar Council’s six circuits in England and Wales, said: “Mr Grayling, who is also our Lord Chancellor, does not appreciate the value of what he is so casually about to destroy.

“So do not weep for barristers. But feel some unease at the irreparable harm about to be done to a system which for a very long time has produced independent, free-spirited men and women whose quality ensured that the standard of British criminal justice was something to be proud of.”

It added: “Mr Grayling knows full well that the net earnings of the vast majority of the state-funded criminal bar are about £35-£40 per hour – significantly lower than most teachers and doctors.

“The Ministry hope to justify the cuts by relying on public misconceptions about what criminal barristers earn and broadcasting the gross fees of a select few at the very top of the profession.”

The letter concluded that barristers who find their earnings reduced at the criminal Bar will find work elsewhere, leaving the criminal justice system short of lawyers.

“They are generally able people who will find something else to do,” it added.

The authors, led by Andrew Langdon QC, leader of the Bar’s western circuit, said Mr Grayling’s cuts will see fees reduced by 15 to 20 per cent on top of a 35 per cent cut in real terms since 2007.

A Ministry of Justice spokeswoman said: “We do not believe we have proposed unjust rates. We have tried to ensure our proposals have more impact on those who earn very high amounts than the more junior Bar.

“For example we know that 70 per cent of barristers contracted to carry out ‘Very High Cost Cases’ receive fee incomes of over £100,000 from criminal legal aid, hence our proposal to cut these fees by 30 per cent.”

For less complex work the minimum a QC would be paid each day will be £306 under the proposals, she added.

Currently about £2 billion a year is spent on legal aid, including £1 billion on criminal cases.